Jase,
I now have the latest version of CCDCommander which includes those options, but I hve also confirmed that they do not impact the TheSky/CCDSoft plate solve process at all, so they are not the source of my problem
It still seems the overwhelming majority of people expect that my FOV is too small for a high rate of successful plate solve in many areas of the sky.
I have re-calculated my FOV and it's actually 10.85 x 7.23 arc minutes, different to what I had remembered but not by a huge amount.
I am yet to have a clear night to try longer exposures.
Thanks,
Roger.